Floating wind turbine systems and methods

ABSTRACT

A system that comprises a hull assembly that includes a plurality of outer columns including a first outer column, a second outer column and a third outer column, the plurality of outer columns surrounding and spaced about a central axis Y.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional of and claims the benefit of U.S.Provisional Application No. 63/276,082, filed Nov. 05, 2021, entitled“SELF-UPENDING FLOATING WIND PLATFORM SYSTEMS AND METHODS,” withattorney docket number 0105198-037PR0. This application is herebyincorporated herein by reference in its entirety and for all purposes.

This application is a non-provisional of and claims the benefit of U.S.Provisional Application No. 63/276,086, filed Nov. 05, 2021, entitled“DOWNWIND FLOATING WIND TURBINE AND ITS CONTROL SYSTEM,” with attorneydocket number 0105198-038PR0. This application is hereby incorporatedherein by reference in its entirety and for all purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is first side view of an example embodiment of a floating windturbine.

FIG. 1 b is a second side view of the example embodiment of the floatingwind turbine of FIG. 1 a .

FIG. 2 a is first side view of another example embodiment of a floatingwind turbine.

FIG. 2 b is a second side view of the example embodiment of the floatingwind turbine of FIG. 1 a .

FIG. 3 is a perspective view of a further example embodiment of the hulland tower of a floating wind turbine.

FIG. 4 is a side view of a floating wind turbine in a near horizontal ornon-vertical configuration.

FIG. 5 is a side view of an articulating tug barge with retractable ramsin accordance with an embodiment.

FIG. 6 is a top perspective view of a rigid arm single point mooring(SPM) buoy system in accordance with an embodiment.

FIG. 7 is a perspective view of a nacelle that includes a wind turbinecomprising three turbine blades.

FIG. 8 illustrates an example embodiment of a self-upending floatingwind turbine in an upright (e.g., operational) configuration.

FIG. 9 is a close-up view of a lower portion of the floating windturbine of FIG. 8 .

FIG. 10 illustrates an example embodiment of a self-upending floatingwind turbine in a folded (e.g., transport) configuration.

FIG. 11 illustrates an example embodiment of a self-upending floatingwind platform during an upending operation.

FIG. 12 illustrates another example embodiment of a floating windturbine that has three outer columns.

FIG. 13 a illustrates an example of an upwind floating wind turbinewhere the central axis Y of the tower is at a heel angle of 0° with arotor tilt angle of 5°.

FIG. 13 b illustrates the upwind floating wind turbine of FIG. 13 a at aheel angle of 10°.

FIG. 14 a illustrates an example of a downwind floating wind turbinewhere the central axis Y of the tower is at a heel angle of 0° with arotor tilt angle of 5°.

FIG. 14 b illustrates the downwind floating wind turbine of FIG. 14 a ata heel angle of 10°.

FIG. 15 illustrates an example of a downwind floating wind turbine witha teetering rotor.

FIG. 16 is a block diagram of a wind turbine controller method.

FIG. 17 a illustrates an example embodiment of a downwind floating windturbine under static conditions with a static tilt angle of 5° and aheel angle of 0° which in this example causes an Annual EnergyProduction (AEP) reduction of 0.4% compared to a tilt angle of 0°.

FIG. 17 b illustrates an example embodiment of a passive downwindfloating wind turbine under rated thrust conditions with a static tiltangle of 5° at a heel angle of 10° that causes a rotor misalignment of-5°, which in this example causes an AEP reduction of 0.4% compared to arotor misalignment of 0°.

FIG. 18 a illustrates an example embodiment of an upwind floating windturbine under static conditions with a static tilt angle of 5° and aheel angle of 0°, which in this example causes an AEP reduction of 0.4%compared to a tilt angle of 0°.

FIG. 18 b illustrates an example embodiment of a passive upwind floatingwind turbine under rated thrust conditions with a static tilt angle of5° at a heel angle of 5° that causes a rotor misalignment of 10°, whichin this example causes an acceptable AEP reduction of 1.5% compared to arotor misalignment of 0°.

FIG. 18 c illustrates an example embodiment of a passive upwind floatingwind turbine under rated thrust conditions with a static tilt angle of5° at a heel angle of 10° that causes a rotor misalignment of 15°, whichin this example causes an unacceptable AEP reduction of 3.4% compared toa rotor misalignment of 0°.

It should be noted that the figures are not drawn to scale and thatelements of similar structures or functions are generally represented bylike reference numerals for illustrative purposes throughout thefigures. It also should be noted that the figures are only intended tofacilitate the description of the preferred embodiments. The figures donot illustrate every aspect of the described embodiments and do notlimit the scope of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One advantage of deploying some embodiments of floating wind turbinesoffshore over bottom-fixed wind turbines can be that such floating windturbines can be assembled and commissioned using onshore cranes andmachinery and then towed out to site. However, the access to many portsaround the world can be hindered by bridges or other obstacles (e.g.,airport regulations) that can constrain the distance a structure risesfrom the sea level (known as the ‘air draft’). Much of the world’sexisting infrastructure has been driven by the global shipping industry,which has standardized vessel classes (e.g., PANAMAX, CHINAMAX, etc.).Air draft allowances can be 50-70 m in some examples. Some wind turbinescan have hub heights in excess of 100 m, rendering many large ports orshipyards inaccessible.

The present disclosure in one aspect provides systems and methods foraccessing these ports by articulating the wind turbine to a horizontalposition during transit. Once located in deeper waters, past theobstruction, the turbine can then be upended into an erectedconfiguration. Furthermore, many ports can have draft restrictions thatcan be as low as 7 m-8 m. By transporting the turbine in a horizontalposition, the wind turbine, the draft can be reduced in variousembodiments.

Another benefit of some examples discussed herein can be to reduceloading on the wind turbine and floating hull structure in extreme windor fault events. The turbine tower, in some embodiments, can be forcedto articulate to a horizontal (or near horizontal) position either bystrong winds or by the inclusion of a motor, actuator, or the like. Whenthe turbine is in such a position, the loads on the turbine and thefloating hull can be reduced. During a turbine fault event, the forcesfrom the turbine may not be directly transferred to the hull in someexamples. Instead, the energy can be dissipated through the viscousdamping of the turbine sub-structure in various embodiments.

Current wind turbines can be robust on land and on fixed offshore windplatforms but their usage on floating platforms typically requireselaborate control systems or large platforms. These platform controlsystems are costly to install and difficult to maintain and operate asthey require regular maintenance. In some wind turbines, the rotor istilted upward by 4-8 degrees in order to increase the clearance betweenthe blade tips and tower in operation. This angle relative to thehorizontal is referred to as the shaft axis, as the main shaft of thewind turbine is from the generator or gearbox to the hub to transmittorque from the rotor.

A wind turbine described in various embodiments of the presentdisclosure includes a downwind turbine, where the rotor is oriented 4-8degrees upward from the horizontal in order to increase the clearancebetween the blade tips and tower in operation. The wind turbine invarious examples produces a thrust force in order to produce power fromthe wind. The thrust force can result in an overturning moment on theplatform, which can cause the platform to have a mean heel angle. Here,a heel angle can be the mean pitch angle of the platform, in thedirection of the wind.

In some examples of a floating wind platform, the target design heelangle is the heel angle of the platform when it is subject to the ratedthrust force of the turbine. Generally, the rated thrust force is themaximum mean thrust force on the turbine during operation. The designheel angle of a platform can depend on the restoring force of theplatform and mooring system, which can be a function of its center ofgravity and buoyancy, its waterplane moment area of inertia and therestoring force due to the mooring system. In general, increasing theplatform’s hydrostatic stiffness can result in increased cost orcomplexity of the system, or both. For instance, for a conventionalsemi-submersible floating wind platform, the hydrostatic stiffness canbe increased by increasing the spacing of the columns, increasing thesize of the columns, or both. Wind platforms, without active platformcontrol systems, can target a design heel angle of 4-5 degrees, so thatthat the maximum rotor misalignment is 8-13 degrees from the horizontal.In various embodiments, the power of the turbine is a function of theswept area of the rotor. The swept area decreases as function of thetilt angle of the turbine as function of the cosine of the tilt angle(gamma). Mathematically,

P = 0.5^(∗) rho^(∗)Cp^(∗)A^(∗)cos(gamma)^(∗)V^3

Where rho is air density, Cp is power coefficient, A is swept area ofblades, gamma is tilt angle of turbine, V is velocity of wind.

Some embodiments include a floating, downwind fixed-hub turbine thatpassively operates at a mean heel angle. For example, to produce powerthrust is produced, and such thrust can cause the platform to tilt(heel) over in the direction of the wind. By designing a floating windturbine that has a mean heel angle of 10 degrees, for example, then invarious embodiments you have the same rotor misalignment as an upwindturbine that is oriented vertically, such as one on land (+/- 5degrees). By designing a platform that has a mean heel angle of 15degrees, for example, then you have the same rotor misalignment as anupwind turbine on a floating platform with a heel angle of 5 degrees.

Some embodiments include a floating, downwind teetered turbine thatpassively operates at a mean heel angle. By designing such floating windturbine that has a mean heel angle of 15 deg, for example, in variousembodiments you then can have less rotor misalignment than an upwindturbine that is oriented vertically (e.g., 0 deg vs +5 degrees).

Some wind platforms, with active platform control systems, can target adesign heel angle of 5-8 degrees, so that the tower can remain verticaland the maximum rotor misalignment can be maintained at 4-8 degrees.Some wind turbines can have larger active control systems which cancause an increased tilt angle, resulting in 0 degrees rotormisalignment. However, a need exists for an improved floating-specificwind turbine and method for its control in an effort to overcome theaforementioned obstacles and deficiencies of some examples of windturbine systems.

In various embodiments, a benefit of a tilting, downwind floating windturbine operating at a tilt angle can be that the wake generated by thefloating wind turbine can be driven down and have a reduced effect onthe downstream floating wind turbine where a plurality of floating windturbines are disposed in an array, group or farm. In variousembodiments, this can allow more floating wind turbines to be packedinto in a given area, which can be a large concern for floating windturbine operators and other stakeholders (fishing, e.g.,).

Below are described example systems and methods, that in accordance withsome embodiments, can be used to design lighter, more inexpensivefloating wind turbines including towers and supporting hull platforms.For example, various embodiments can include a floating wind turbinecomprising one or more of:

-   (1) A one-, two- or three-bladed wind turbine (e.g.,    horizontal-axis: upwind or downwind rotor, or vertical-axis).-   (2) A platform comprising of multiple, buoyant assemblies (e.g., 4    such assemblies). For example, in some embodiments the assemblies    can comprise four-bar linkages using members connected by pin    bearings or other suitable element. The assemblies in some examples    contain a main buoyant member (e.g., a column). In one embodiment,    each of the assemblies are connected to a central column.-   (3) A moveable truss member for each assembly, such that each    assembly can be reconfigured depending on the position of said truss    member. In various examples, when the truss member is connected the    final position of the assembly is determined. In one embodiment, the    final position of the assembly is such that the column is oriented    vertically.

One embodiment can be designed so that platform is as shown in FIG. 8 .Such a design can comprise, consist essentially of, or consists of oneor more of the following elements, with one or more of such elementsbeing specifically absent in some embodiments.

(a) Multiple buoyant columns that can have a variable amount of mass(such as partially or fully filled ballast tanks).

(b) Multiple, independent assemblies, such that the horizontal members(e.g., the upper and lower truss members in FIG. 8 ) form a four-barlinkage with the central column and a buoyant structure (e.g., an outercolumn). Each of the structural members can connected by pin bearings insome examples.

(c) A diagonal cross-beam for one or more pinned structure.

(d) A mechanism to allow the end of the cross-beam to transit across thecentral column/tower.

One embodiment comprises, consists essentially of, or consists of afloating downwind turbine with a turbine control system that can be usedto optimize the tilt angle of the platform.

Another embodiment comprises, consists essentially of, or consists of afloating downwind turbine with a teetered hub, and a turbine controlsystem that can be used to optimize the teeter angle of the rotor andthe tilt angle of the platform.

In some such embodiments, no active control system exists on theplatform, as the platform can be allowed to passively pitch or tilt inthe direction of the wind. However, in various examples, the turbine isable to produce full power, as the rotor plane can remain aligned withthe horizontal.

Turning to FIGS. 1 a, 1 b, 2 a and 2 b , two example embodiments 100A,100B of a floating wind turbine 100 are illustrated in FIGS. 1 a and 1 band in FIGS. 2 a and 2 b respectively. The floating wind turbine 100 isshown comprising a tower body 110 having a tower shaft 112 that extendsalong an axis Y. The tower body 110 further comprises a tower base 114at a bottom end of the tower shaft 112, with a keel plate 116 disposedat a terminal bottom end of the tower body 110. One or more fins 118 canextend between the keel plate 116 and tower base 114 to reinforce acoupling between the keel plate 116 and tower base 114 and/or providedampening for rotation, movement or pitch of the tower 110.

A nacelle 170 can be disposed at a top end of the tower body 110. Thenacelle 170 can be configured in various suitable ways and comprisevarious suitable elements, including a wind turbine 700 comprising a hub172 with a plurality of blades 174 extending from the hub 172 as shownin the example of FIG. 7 . Further embodiments can include any suitableplurality of blades 174, including 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,16, 24, 36, 48, or the like. In some embodiments, a wind turbine 700 canoperate in a horizontal-axis with and upwind or downwind rotor or canoperate in a vertical-axis.

Various embodiments can include any suitable turbine elements, so theexample of FIG. 7 should not be construed as being limiting.Additionally, while various example embodiments herein relate to windturbines, it should be clear that further embodiments can be employedfor various suitable purposes including a light house, bridge,communications array, weather station, observation station, weaponmount, or the like.

Returning to FIGS. 1 a, 1 b, 2 a and 2 b , the floating wind turbine 100is further shown comprising a hull 130 that includes a pair of baseelements 132 and a pair of support architectures 134, which are spacedapart and coupled together via one or more bars 136. As shown in theexamples of FIGS. 1 b and 2 b , the pair of base elements 132A, 132B,the pair of support architectures 134A, 134B and the one or more barscan define a hull cavity 138.

A pitch plate 140 can extend between the support architectures 134A,134B and be rotatably coupled to the hull 130 via pitch shaft 142, whichallows the pitch plate 140 to rotate about an axis X. The tower shaft112 and/or tower base 114 can extend through and be coupled to the pitchplate 140, which can allow the tower 110 to rotate about the axis X viathe pitch plate 140. In various embodiments, axis Y of the tower 110 canbe perpendicular to and/or coincident with the axis X. As shown in theexamples of FIGS. 1 a, 1 b, 2 a and 2 b (and also FIG. 3 discussed inmore detail herein), such rotation of the tower 110 via the pitch plate140 can allow the tower base 114 and/or keel plate 116 to swing or pitchwithin the hull cavity 138 to various configurations as discussedherein.

Additionally, the tower 110 can be coupled to the pitch plate 140 via ayaw bearing 144, which can allow the tower shaft 112 and/or tower base114 to rotate about axis Y of the tower 110. Providing for rotation ofthe tower 110 about the axis Y can be desirable in some embodiments toposition the nacelle 170 in a desired or optimal direction, such as atan angle where a wind turbine 700 associated with the tower 110 producesa maximum amount of energy, produces a maximum amount of energy withoutcompromising structural integrity of the blades 174, to protect theblades 174 from wind damage, and the like. Additionally, in someembodiments, the nacelle 170 can be rotatably coupled to the top of thetower 110 in addition to or as an alternative to a yaw bearing 144. Insome embodiments (e.g., downwind turbine embodiments), there may be ormay not be a yaw motor or actuator that actively drives yaw rotation ofthe tower 110 about central axis Y. In some examples, wind turbineweathervanes can be downwind and the yaw bearing 144 can allow passiverotation of the tower 110 relative to the hull 130. In anotherembodiment, a conical bearing can allow free yaw motion of the tower110, while the hull 130 can be split (e.g., as shown in FIGS. 1 a, 1 b,2 a and 2 b ).

In an upwind turbine embodiment, the yaw bearing 144 can replace theneed for a yaw controller in the nacelle 170. In one such embodiment, amotor can drive the yaw bearing 144 so that the nacelle 170 faces intothe wind. In this configuration, in some examples, it can be desirablefor the axis X of the pitch shaft 142 to be perpendicular to theincident wind direction to minimize off-axis loading on bearings orother elements of the floating wind turbine 100.

The floating wind turbine 100 can be configured to float and be disposedon the surface 101 of a body of water 102 with a portion of the floatingwind turbine 100 being disposed within the body of water 102 and aportion of the floating wind turbine 100 being disposed above 103 thebody of water 102. For example, in the embodiments 100A, 100B of FIGS. 1a, 1 b, 2 a and 2 b , the nacelle 170, tower shaft 112, pitch plate 140,pitch shaft 142, yaw bearing 144, and axis X are shown being disposedabove 103 the surface 101 of the body of water 102. A portion of thetower base 114 and support architectures 134 are shown as beingpartially above 103 and within the body of water 102. The base elements132 of the hull 130 and keel plate 116 of the tower 110 are shown beingbelow the surface 101 of the body of water 102. The floating windturbine 100 can be disposed in any suitable body of water or fluid,including an ocean, lake, river, man-made body of water, or the like.

Further embodiments can be configured for various elements of thefloating wind turbine 100 to be positioned in various suitable locationsrelative to the surface 101 of a body of water 102 that the floatingwind turbine 100 is floating on, so the examples of FIGS. 1 a, 1 b, 2 aand 2 b should not be construed to be limiting. Additionally, asdiscussed herein, the buoyancy of the floating wind turbine 100 can bemodified in various embodiments, which may change which elements areabove 103 or within the body of water 102 at a given time. In someembodiments, it can be desirable to have elements such as at least aportion of the tower base 114 and the keel plate 116 disposed within thebody of water 102 to provide resistance to or dampening of rotation ofthe tower 110.

For example, in some embodiments, one or more fins 118 can have a planarface that is parallel to the axis of rotation X, which can provide asurface area that provides resistance to or dampening of rotation of thetower 110 based on friction between such a surface area and water 102 inwhich the fins 118 of the tower rotate 110. Additionally, in someembodiments, it can be desirable to have elements such as the pitchplate 140, pitch shaft 142, and/or yaw bearing 144 disposed above thesurface 101 of the water 102 to prevent or reduce water intrusion,corrosion, or the like, of such elements.

In various embodiments, it can be desirable to fix or substantially fixthe floating wind turbine 100 in a location on the surface 101 of thewater 102. For example, it can be desirable to prevent the floating windturbine 100 from drifting away or preventing the floating wind turbine100 from contacting undesirable objects such as another floating windturbine 100 (e.g., in a wind farm), a reef, a beach, rocks, a cliff, orthe like. In various embodiments, including the examples of FIGS. 1 a, 1b, 2 a and 2 b , one or more mooring lines 150 can be coupled to thefloating wind turbine 100 to fix or substantially fix the floating windturbine 100 in place. For example, such one or more mooring lines 150can coupled to various suitable locations on the hull 130 such as thesupport architecture 134 (see FIGS. 1 a and 1 b ) base element(s) 132(see FIGS. 2 a and 2 b ), or the like. Mooring lines 150 in someexamples can be coupled to weights or anchors at an ocean floor,lakebed, riverbed or the like.

In some embodiments, the floating wind turbine 100 can be connected to aturret system or a single point mooring buoy, such as those on FloatingProduction, Storage and Offloading units (FPSOs). An example of such amooring buoy system 600 is shown in FIG. 6 . In some embodiments, such aturret system can either be driven to rotate upwind or be passivelyallowed to weathervane downwind.

In various embodiments, the floating wind turbine 100 can generateelectrical power (e.g., via wind turning a wind turbine 700 asillustrated in the example of FIG. 7 ) and generated electrical powercan be transmitted to various locations via one or more electricalcables 155, which in various embodiments can extend from the bottom ofthe keel plate 116 as shown in FIGS. 1 a and 1 b . For example, in someembodiments, the electrical power generated by a floating wind turbine100 can be transmitted to land, a battery station, another floating windturbine 100, a water-based electrical power consumer (e.g., a floatinghome, ship, station, or the like). Additionally, in some embodiments,one or more electrical cables 155 can be configured to provideelectrical power to a floating wind turbine 100, which can be receivedfrom land, a battery station, another floating wind turbine 100, or thelike.

Turning to FIG. 3 , a portion of further embodiment 100C of a floatingwind turbine 100 is illustrated, which includes a tower 110 that isrotatably coupled to a hull 130 via a pitch shaft 142. In this exampleembodiment 100C, the hull 130 can comprise one or more floater modules334 that surround the tower 110 and one or more connectors 336 extendingbetween floater modules 334. In some examples, the connectors 336 cancomprised hinged connections that stiffen the hull 130, but allow forthe tower 110 upending as discussed herein.

A yaw unit 344 can be disposed at a top end of the hull 130, with a pairof pitch units disposed on the yaw unit 344 that hold the pitch shaft142 and can allow the tower 110 to rotate via the pitch shaft 142. Thefloater modules 334, connectors 336 and yaw unit 344 can define a hullcavity 338 through which the tower 110 can extend and pitch or rotatevia the pitch shaft 142. The yaw unit 344 can be configured to rotate toallow the tower 110 to rotate about a central axis (e.g., axis Y asshown in FIGS. 1 a, 1 b, 2 a and 2 b ). The hull 130 can furthercomprise one or more fairleads 350 that allow mooring lines 150 tocouple with and secure the floating wind turbine 100 as discussedherein.

In various embodiments, the base of the yaw unit 344 can comprise afloating body that is designed in a “C” shape that can allow for 90degrees of pitch rotation for the tower 110 of the floating wind turbine100. In some embodiments, connectors 336 can be hinged and can allow forthe tower 110 to articulate when the connectors 336 are opened, and whenthe connectors 336 are closed, can provide load transfer throughout thestructure of the hull 130.

In some embodiments, pitch bearings can be disposed on the tower 110 andthe pitch shaft 142 can comprise a retractable ram that allows the tower110 to disconnect from the floating hull 130. In various examples, suchan assembly can be used with an articulating tug barge 500, as shown inFIG. 5 . In another embodiment, the tower 110 can be connected to thehull 130 via a hinged joint. In order to up-end the turbine in someexamples, internal cables can be tensioned. In one such an embodiment,the floating hull 130 can be in a more structurally efficient toroidalshape.

As discussed herein, in various embodiments a pitch shaft 142, or thelike, can allow the tower 110 of the floating wind turbine 100 to assumea vertical or near-vertical configuration (e.g., for power-producing) asshown in the FIGS. 1 a, 1 b, 2 a and 2 b or horizontal ornear-horizontal configuration (e.g., for installation, transit, loadmitigation) as shown in FIG. 4 . For example, FIG. 4 illustrates anembodiments 100A of a floating wind turbine 100 where the central axis Yof the tower 110 is in a near-horizontal configuration and disposedalong axis Y1, with the tower 110 being configured to pitching aboutpitch shaft 142 an angle θ to assume a vertical or near-verticalconfiguration where the central axis Y of the tower 110 is disposedalong axis Y2. In various embodiments, configuration or axis Y2 can bevertical or near-vertical relative to gravity, the plane W of thesurface 101 of the body of water 102 that the floating wind turbine 100is floating on, a main horizontal axis of the floating wind turbine 100,or the like.

In some embodiments, a floating wind turbine 100 can be configured topitch or rotate any suitable angle θ from a vertical or near-verticalconfiguration (e.g., from axis Y2), including positive and/or negative45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 110°,115°, 120°, 125°, 130°, 135°, or the like. For example, some embodimentscan be configured to rotate in only one direction from a vertical ornear-vertical configuration or can be configured to rotate or pitch bothdirections from a vertical or near-vertical configuration. In someembodiments, a maximum rotation in both directions can be the same orcan be different (e.g., any of the example values cited above). In someembodiments, the tower 110 can be configured to pitch or rotate andamount that prevents the tower 110, nacelle 170 or a wind turbine of thenacelle 170 from extending into the water 102 or engaging the surface101 of the water 102; however, some embodiments can be configured forthe tower 110, nacelle 170 and/or a wind turbine of the nacelle 170 toextend into the water 102 or engage the surface 101 of the water 102.

In various embodiments, rotation or pitch of the tower 110 can beconfigured based on the ability of the hull 130 to rotate, pitch or moveon the surface 101 of the water 102 due to waves, wind, storms, or thelike. In some examples, the orientation of the tower 110 can be activelycontrolled relative to the hull 130 such that the tower 110 can bemaintained at a vertical or near-vertical configuration even if the hull130 rotates, pitches or moves on the surface 101 of the water 102. Forexample, the orientation of the tower 110 and/or hull 130 can bemonitored and determined relative to a desired vertical or near-verticalconfiguration and a motor, actuator, or the like can actively change tothe orientation of the tower 110 toward the desired vertical ornear-vertical configuration despite rotation, pitch or movement of thehull 130 on the surface 101 of the water 102.

One embodiment of a method of operating a floating wind turbine 100 caninclude determining an orientation of the tower 110 and/or hull 130;determining whether the tower 110 is in an orientation that is not avertical or near-vertical configuration or within a margin of error of avertical or near-vertical configuration based at least in part on thedetermined orientation of the tower 110 and/or hull 130; and actuatingthe tower 110 (e.g., about the pitch shaft 142) to move the tower 110toward the desired vertical or near-vertical configuration or within amargin of error of the desired vertical or near-vertical configuration.In some embodiments, such a method can be performed in real time, nearreal-time, or every 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 10.0seconds, or the like.

A floating wind turbine 100 where the tower 110 is configured to assumea horizonal, near horizontal or non-vertical configuration can bedesirable for operations such as installation of the floating windturbine 100, assembly of the floating wind turbine 100, transit of thefloating wind turbine 100, maintenance of the floating wind turbine 100,load mitigation of the floating wind turbine 100, or the like. Forexample, FIG. 4 illustrates an example embodiment, where tow lines 410are coupled to the hull 130 of the floating wind turbine 100, which canbe used to move the floating wind turbine 100.

Additionally, in some examples, where a determination is made that windsor other weather conditions could cause damage to elements the floatingwind turbine 100 (e.g., blades 174, tower shaft 112, or the like), thetower 110 can be automatically or manually lowered to a horizonal, nearhorizontal or non-vertical configuration to protect the floating windturbine 100 from damage. For example, a method of operation of afloating wind turbine 100 can include determining that wind or weatherconditions are above or are predicted to be above a safety threshold,and if so, lowering the tower 110 to a horizonal, near horizontal ornon-vertical configuration to protect the floating wind turbine 100.Such a determination can be made by one or more weather, wind or othersensors at the floating wind turbine 100, at another floating windturbine 100, by a weather station, by an onshore device, or the like. Insome embodiments, a computing device of the floating wind turbine 100can make such a determination based on local and/or remote data and canautomatically lower the tower 110 without user input, alert a user tothe danger and receive instructions to lower the tower 110, or the like.In some examples, lowering of the tower 110 can be performed by a motoror other actuator and in some examples, the tower 110 changed from beingin a locked configuration to an unlocked configuration, which can allowthe tower 110 to fall or lower under its own weight.

In various embodiments, portions of the floating wind turbine 100 can beconfigured to have or contain a variable amount of mass or ballast. Insome embodiments, a portion of the tower base 114 or portion of thetower 100 below the pitch shaft 142 can be configured for mass orballast to be added or removed therefrom. For example, in variousembodiments, the tower base 114 and/or keel plate 116 can comprise acavity in which a ballast material (e.g., sand, weights, water or thelike) can be introduced or removed from. In further embodiments, ballastor mass (e.g., weights, sandbags, water bladders, or the like) can becoupled to or removed from the tower base 114 and/or keel plate 116.

Such an addition of such ballast material can lower the center ofgravity of the tower 110 in various examples such as from a first highercenter of gravity CG1 to a lower center of gravity CG2 as shown in FIG.3 . In various embodiments, addition of such ballast material can lowerthe center of gravity of the tower 110 from being above the pitch shaft142 to below the pitch shaft 142 (see e.g., FIG. 3 ), which can cause ormake it easier for the tower 110 to rise from a horizontal, nearhorizontal, or non-vertical configuration (see e.g., FIG. 4 ) to avertical or substantially vertical configuration (see e.g., FIGS. 1 a, 1b, 2 a, and 2 b ). In further embodiments, adding ballast can lower thecenter of gravity of the tower 110 from first position above the pitchshaft 142 to a second position above the pitch shaft 142 or can lowerthe center of gravity of the tower 110 from first position below thepitch shaft 142 to a second position below the pitch shaft 142.

A single floating wind turbine 100 or an array of a plurality offloating wind turbines 100 can be manufactured, erected or positioned invarious suitable ways with various portions occurring on land and/or abody of water 102. For example, in some embodiments, during fabricationand/or assembly of the hull 130 and tower 110, the tower 110 can beeither in a vertical position or in a horizontal position. In oneembodiment, the nacelle 170, wind turbine 700 and/or blades 174 can bemated with the tower 110 in a horizontal position or substantiallyhorizontal position. Such an embodiment in some examples can usesmaller, more readily available cranes to lift the tower 110 or sectionsthereof, along with the nacelle 170 and/or blades 174 of the windturbine 700. In some examples, before, during, or just afterinstallation of the nacelle 170, wind turbine 700, blades 174, or thelike, ballast (e.g., solid or liquid ballast) can be added to the towerbase 114 to balance out the weight of such elements. In one embodiment,the solid ballast can take the form of batteries. In some embodiments,ballast can be added incrementally as additional elements are installedon the tower 110, nacelle 170 or the like.

In one embodiment, the amount of ballast added can be calculated so thatthe vertical center of gravity of the tower 110 (including a nacelle 170wind turbine 700, and the like) is located at or substantially the pitchaxis X (see e.g., FIGS. 1 b and 2 b ). In such an embodiment (in theabsence of friction), there may be no resultant overturning moment fromthe weight of the turbine 700, tower 110, or the like, on the hull 130.Such an embodiment may reduce the holding force required to keep thefloating wind turbine 100 in a horizontal, near horizontal position ornon-vertical position and may also reduce the force required to rotatethe tower 110 relative to the hull 130 (e.g., to or from a vertical ornear vertical position).

In some embodiments, once the tower 110 has been integrated onto thehull 130 on or near land (e.g., via the pitch shaft 142, in variousexamples the assembled floating wind turbine 100 can be towed from aport to a location on a body of water 102 where the floating windturbine 100 will be installed. Many ports have draft or air draftrestrictions as previously described, which can be the distance from thesurface of the water 101 to a highest point on a vessel, cargo on avessel or cargo being towed by a vessel. Draft restrictions can be lessthan or equal to 7 m, 8 m, 9 m, 10 m, 12 m or the like. Air draftrestrictions can be less than or equal to 35 m, 40 m, 45 m, 50 m, 55 m,60 m, 70 m, 75 m, 80 m, 85 m, 90 m, or the like. Once these obstructionsor restrictions have been cleared, the platform can be reconfigured tohave a larger draft, or a larger air draft or both a larger draft and alarger air draft.

In one embodiment, the tower base 114 and/or keel plate 116 can befilled with sand, gravel, dirt or the like, away from the port (e.g.,once any port obstructions and/or restrictions have been cleared), sincesuch a material may be a readily available, low-cost solid ballastoption. Furthermore, on return to the port or land for a maintenanceoperation where lowering the tower 110 may be necessary or desirable,such a ballast material can simply be dropped to the seafloor, ifnecessary, without harming the environment, which can allow the tower110 to be lowered or more easily lowered. After the maintenanceoperation and when the floating wind turbine 100 is being re-installedor installed in a new location on a body of water 102, new ballast canagain be added to the tower 110 as discussed herein to raise the tower110 or to make raising the tower 110 easier (e.g., tower pitch motorsmay be incapable of raising the tower without the addition of asufficient amount of ballast.

In various embodiments, once the additional ballast has been added, thevertical center of gravity of the tower 110 can be dropped below thepitch axis X (see e.g., FIG. 3 ). This can result in the wind turbinetower 110 being up-ended and in a vertical or near-vertical position.The floating wind turbine 100 can then be towed (e.g., via tow lines410) to an offshore wind farm site, so it can be installed (e.g.,connected to a mooring and/or cabling system comprising mooring lines150, electrical cables 155, or the like) . In another embodiment, thefloating wind turbine 100 can be towed with the tower 110 in ahorizontal, near horizontal or non-vertical position (e.g., as shown inFIG. 4 ) so that the drag on the tower 110 and associated elements canbe reduced. In such an embodiment, the turbine upending can occur at thewind farm site (e.g., via adding ballast, a pitch motor, crane, or thelike).

In various examples, after the hull 130 is connected to the cable and/ormooring systems, the turbine 700 can be commissioned. In one embodimentwith an upwind horizontal-axis wind turbine, the horizontal center ofgravity of the tower 110 is located towards the hub 172 of the nacelle170. A static overturning moment can result and the turbine 700 can betilted into the wind. An optimal static tilt angle into the wind in someexamples may be in the range of 5-15 degrees, 7-13 degrees, 9-11degrees, 4-17 degrees, 3-19 degrees, 2-20 degrees, and the like. Forcertain low wind speeds, the tilt of the turbine 700 can result inincreased power production since the tilt angle of the turbine 700 canoffset the tilt angle of the nacelle 170 in various embodiments. Inhigher wind speeds, in some examples the turbine 700 can tilt out of thedirection of the wind.

In some embodiments, fins 118 can added to the base 114 and or keelplate 116 of the tower 110 which can increase the viscous dampingeffects of the tilting tower 110. In the case of an emergency shutdown,or other event where there is a dramatic change in the thrust force, thefloating wind turbine 100 may exhibit large dynamic tilting motion. Thefins 118 can, in some examples, dissipate the energy from the dynamictilt motion into the surrounding fluid 102 thereby reducing the loadstransferred to the hull 130.

As previously described, if the floating wind turbine 100 is to returnto port for maintenance, decommissioning, or the like, ballast in and/oron the keel plate 116 and/or tower base 114 can be removed. This candecrease the draft of the floating wind turbine 100, allowing it toenter a port with draft restrictions. Furthermore, the tower 110 can bemoved into a horizontal position in various examples without the needfor large tugboats when the vertical center of gravity aligns with or isclose to the pitch axis X (e.g., based on addition or removal ofballast).

Accordingly, a method of installing at least one floating wind turbine100 can include one or more of the follow steps, which can start withassembling at least a portion of a tower 110 and hull 130 floating windturbine 100 and then coupling the tower 110 to the hull 130 (e.g., via apitch shaft 142). Some or all of such assembly can occur on landincluding at a port or shoreline, or away from a port or shoreline. Forexample, the tower 110 and hull 130 (or portions thereof) can betransported to a port or shoreline as separate pieces, with the tower110 and hull 130 (or portions thereof) being assembled to form a full orsubstantially complete floating wind turbine 100.

Such a full or substantially complete floating wind turbine 100 can havethe tower 110 in a horizontal or near horizontal configuration whilebeing assembled and/or during a portion of a journey from a port orshoreline to a desired location where the floating wind turbine 100 isto be installed. When possible or desirable, the floating wind turbine100 can be converted from the tower 110 being in the horizontal or nearhorizontal configuration to an erected configuration where the tower 110is in a vertical or near vertical configuration.

For example, as discussed herein, in some embodiments erecting the tower110 can include adding ballast into and/or on a portion of the tower 110to change the center of gravity of the tower 110, which can cause thetower 110 to self-erect or may make it possible for a pitch actuator,crane, or the like to erect the tower 110. In various embodiments, sucha method or portions thereof can be performed in reverse when thefloating wind turbine 100 needs to be decommissioned, repaired, loweredor moved to prevent damage that may be caused by wind or weather, or thelike.

Turning to FIGS. 8-11 another embodiment 100D of a floating wind turbine100 is illustrated that comprises a tower 110 coupled to a hull assembly830 that includes with a central column 840 and a plurality of outercolumns 850 that are coupled to the central column 840 via one or morerespective upper truss members 860, one or more respective lower trussmembers 870 and one or more respective cross-beams 880. Note thatelements such as a nacelle, rotor and turbine are not illustrated inthese figures for purposes of simplicity.

The tower 110 can comprise a tower shaft 112 having a central axis Ywith the central column 840 being disposed at a bottom end of the towershaft 112 with the central column 840 sharing the central axis Y. Asshown in the examples of FIGS. 8 and 9 , the floating wind turbine 100can comprise four outer columns 850A, 850B, 850C, 850D that are spacedapart from the central column 840 at an equal distance via the upper andlower truss members 860, 870 and cross-beams 880. In variousembodiments, the outer columns 850 can have separate respective centralaxes that are parallel to the central axis Y of the tower 110 andcentral column 840. In various embodiments, the outer columns 850 and/orcentral column 840 can comprise ballast tanks configured to hold fluidsuch as air and/or water as discussed herein.

Additionally, the four outer columns 850A, 850B, 850C, 850D can beequally spaced about the central column 840 with respective adjacentouter columns 850 being 90° from each other about the central axis Y.For example, the first and third outer columns 850A, 850C can bedisposed in a first common plane that is coincident with the centralaxis Y. The second and fourth outer columns 850B, 850D can be disposedin a second common plane that is coincident with the central axis Y andperpendicular to the first common plane of the first and third outercolumns 850A, 850C.

Also, in various embodiments, the four outer columns 850A, 850B, 850C,850D can be of equal length such that bottoms of four outer columns850A, 850B, 850C, 850D are disposed within a third common plane and topsof the four outer columns 850A, 850B, 850C, 850D are disposed within afourth common plane that is parallel to the third common plane and thatis perpendicular to the central axis Y. In some embodiments, (e.g., a10-15 MW turbine 700) the floating wind turbine can have a rotordiameter of 180-230 m. In various examples, the tower 110 can have aheight of 100-150 m. In various embodiments, the columns 840, 850 canhave a diameter of 8-12 m. In some examples, the outer columns 850 canbe 40-50 m from the central column 840 (e.g., the upper and/or lowertruss members 860, 870 can be 40-50 m long). In some examples thecolumns can have a height of 30-40 m. In various embodiments the columns840, 850 can have an operating draft of 15-25 m.

As shown in the example embodiment 100D of the floating wind turbine 100of FIGS. 8-11 , each outer column 850 can be coupled to the centralcolumn 840 via a pair of upper truss members 860. For example, as shownin FIG. 9 , the first outer column 850A can be coupled to the centralcolumn 840 via first and second upper truss members 860A1, 860A2. Invarious embodiments, the pairs of upper truss members 860 can extendfrom a top end of respective outer columns 850 at an angle with thedistance between the pair of upper truss members 860 increasing towardthe central column 840. For example, such an angle can be 2°, 4°, 6°,8°, 10°, 12°, 14°, 16°, 18°, 20°, 22°, 24°, 26°, or the like, includinga range between such values. In various embodiments the upper trussmembers 860 can be configured to extend toward the central column 840 ina common plane that is perpendicular to the central axis Y.

In various embodiments, the upper truss members 860 can be cylindricalbars as shown in the example embodiment 100D of the floating windturbine 100 of FIGS. 8-11 , but in further embodiments, the upper trussmembers 860 can be any suitable form such as an I-beam, box truss, orthe like. Additionally, in various embodiments, there can be anysuitable number of upper truss members 860 associated with each outercolumn 850 such as 1, 2, 3, 4, 5, 10, 25, 100 and the like. Also,various structures can be associated with the upper truss members 860such as plates, walkways, and the like.

As shown in the example embodiment 100D of the floating wind turbine 100of FIGS. 8-11 , each outer column 850 can be coupled to the centralcolumn 840 via a lower truss member 870. For example, as shown in FIG. 9, the first outer column 850A can be coupled to the central column 840via a first lower truss member 870A, the second outer column 850B can becoupled to the central column 840 via a second lower truss member 870B,the third outer column 850C can be coupled to the central column 840 viaa third lower truss member 870C and the fourth outer column 850D can becoupled to the central column 840 via a fourth lower truss member 870D.

In various embodiments, the lower truss members 870 can comprise varioussuitable structures such as a plate and/or one or more bars (see e.g.,FIGS. 9 and 10 showing a lower truss plate 872 covering a pair of lowertruss bars 874). In some embodiments, where a pair of lower truss bars874 extend from a bottom end of respective outer columns 850, such lowertruss bars can extend at an angle with the distance between the pair ofupper truss members 860 increasing toward the central column 840. Forexample, such an angle can be 2°, 4°, 6°, 8°, 10°, 12°, 14°, 16°, 18°,20°, 22°, 24°, 26°, or the like, including a range between such values.In some examples, such an angle can be the same as upper truss members860. In various embodiments, the lower truss members 870 can beconfigured to extend toward the central column 840 in a common planethat is perpendicular to the central axis Y, and in some examples such acommon plane can be parallel to a common plane of upper truss members860.

In various embodiments, the lower truss bars 874 can be cylindricalbars, but in further embodiments, such lower truss bars 874 or the lowertruss members 870 can be any suitable form such as an I-beam, box truss,or the like. Additionally, in various embodiments, there can be anysuitable number of lower truss bars 874 or the lower truss members 870associated with each outer column 850 such as 1, 2, 3, 4, 5, 10, 25, 100and the like.

As shown in the example embodiment 100D of the floating wind turbine 100of FIGS. 8-11 , cross-beams 880 can extend between respective outercolumns 850 and the central column 840 from a bottom end of therespective outer columns 850 to respective locations at a top end of thecentral column 840. However, in further embodiments, cross-beams 880 canextend between respective outer columns 850 and the central column 840from a top end of the respective outer columns 850 to respectivelocations at a bottom end of the central column 840.

For example, as shown in FIG. 9 , the first outer column 850A can becoupled to the central column 840 via a first cross-beam 880A, thesecond outer column 850B can be coupled to the central column 840 via asecond cross-beam 880B, the third outer column 850C can be coupled tothe central column 840 via a third cross-beam 880C and the fourth outercolumn 850D can be coupled to the central column 840 via a fourthcross-beam 880D.

Additionally, the four cross-beams 880A, 880B, 880C, 880D can be equallyspaced about the central column 840 with respective adjacent cross-beams880 being 90° from each other about the central axis Y. For example, thefirst and third cross-beams 880A, 880C can be disposed in a first commonplane that is coincident with the central axis Y. The second and fourthcross-beams 880B, 880D can be disposed in a second common plane that iscoincident with the central axis Y and perpendicular to the first commonplane of the first and third cross-beams 880A, 880C.

In various embodiments, the cross-beams 880 can be cylindrical bars, butin further embodiments, such cross-beams 880 can be any suitable formsuch as an I-beam, box truss, or the like. Additionally, in variousembodiments, there can be any suitable number of cross-beams 880associated with each outer column 850 such as 1, 2, 3, 4, 5, 10, 25, 100and the like.

In various embodiments, the floating wind turbine 100 can be operable tochange configurations between an erected configuration as shown in FIGS.8 and 9 and a collapsed configuration as shown in FIG. 10 . For example,the outer columns 850 can be individually movably coupled to the centralcolumn 840 such that the outer columns 850 can be folded upward and/ordownward relative to the tower body 110 so that the outer columns 850are retracted closer to the central axis Y to reduce the maximumdimensions of the hull assembly 830, which can be desirable fortransportation of the floating wind turbine 100 in some examples asdiscussed herein.

For example, as shown in FIG. 10 , a first pair of adjacent outercolumns 850B, 850C can be configured to fold downward relative to towerbody 110 so that the outer columns 850 are retracted closer to thecentral axis Y such that this pair of outer columns 850B, 850C isdisposed fully or at least partially below the bottom of the centralcolumn 840. A second pair of adjacent outer columns 850A, 850D can beconfigured to fold upward relative to tower body 110 so that the outercolumns 850 are retracted closer to the central axis Y such that thispair of outer columns 850A, 850D is disposed fully or at least partiallyabove the top of the central column 840 about the tower shaft 112 of thetower body 110.

In various embodiments, such as shown in the example of FIG. 10 , arespective main axis of the outer columns 850 can remain parallel to thecentral axis Y in the collapsed configuration of FIG. 10 and/or duringthe process of the outer columns 850 folding upward or downward from theerected configuration to the collapsed configuration. Such a folding insome embodiments can be based on one or more rotatable couplings betweenthe outer columns 850 and the central column 840 and/or one or moretranslational rotational couplings between the outer columns 850 and thecentral column 840.

For example, respective ends of the upper and lower truss members 860,870 can be rotatably coupled to the respective outer columns 850 and tothe central column 840, which can allow the outer columns 850 torotatably fold up and/or down. Additionally, ends of the cross-beams 880that are rotatably coupled to the central column 840 can be configuredto translate up and/or down the length of the central column 840 and/ortower shaft 112 of the tower body 110 and opposing ends of thecross-beams 880 that are coupled to the respective outer columns 850 canbe rotatably coupled to the respective outer columns 850 such that thecross-beams 880 can fold toward the central column 840 and/or towershaft 112 when the outer columns 850 rotatably fold up and/or down.

For example, referring to FIGS. 9 and 10 , the first pair of adjacentouter columns 850B, 850C can be configured to rotatably fold downwardrelative to tower body 110 with opposing ends of the cross-beams 880B,880C coupled to the central column 840 translating downward along theface of the central column 840 via respective cross-beam lower tracks820 to allow the cross-beams 880B, 880C to fold toward the centralcolumn 840, to the collapsed configuration of FIG. 10 , based onrotatable couplings at the ends of the second and third cross-beams880B, 880C. (The lower track 820B of the second cross-beam 880B is shownin FIG. 9 ). Accordingly, the first pair of adjacent outer columns 850B,850C are folded closer to the central axis Y such that this pair ofouter columns 850B, 850C is disposed fully or at least partially belowthe bottom of the central column 840.

The second pair of adjacent outer columns 850A, 850D can be configuredto rotatably fold upward relative to tower body 110 with the opposingends of the cross-beams 880A, 880D coupled to the central column 840translating upward along the face of the tower shaft 112 of the towerbody 110 via respective cross-beam upper tracks 810A, 810B to allow thecross-beams 880A, 880D to fold toward the tower body 110, to thecollapsed configuration of FIG. 10 , based on rotatable couplings at theends of the first and fourth cross-beams 880A, 880D. Accordingly, thesecond pair of adjacent outer columns 850A, 850D are folded upwardcloser to the central axis Y such that this second pair of outer columns850A, 850D is disposed fully or at least partially above the top of thecentral column 840 proximate to and about the tower shaft 112 of thetower body 110.

Folding of the outer columns 850 from the erected configuration to thecollapsed configuration (and vice versa) can be performed in varioussuitable ways. For example, in some embodiments, the translationalcouplings of the cross-beams 880 in the cross-beam upper and lowertracks 810, 820 can be based on buoyancy of the central column 840and/or outer columns 850 as discussed herein and/or can be motorized(e.g., fluidic, electric, or fuel-powered), which can allow the up anddown movement in the cross-beam upper and lower tracks 810, 820 thatcauses motorized actuation of the outer columns 850 up and/or down.Accordingly, in various embodiments, configuring the floating windturbine 100 between the erected/extended and collapsed configurationscan be motorized based on passive and/or powered translation of thecross-beams 880 in the cross-beam upper and lower tracks 810, 820.

In further embodiments, translation of the cross-beams 880 can bemechanical such as by a user rotating a crank or otherwise applyingexternal mechanical force. In further embodiments, other portions of thefloating wind turbine 100 can be configured to cause actuation of theouter columns 850, such as cables, winches, motors on a rotatablecoupling, or the like. In some embodiments, actuation of the outercolumns 850 can be performed by an external apparatus such as a crane,or the like. In some embodiments, actuation of the outer columns 850 canbe performed based on forces of gravity or buoyancy such as based onballast and/or air being introduced into or removed from the centralcolumn 840 and/or one or more outer columns 850.

In some embodiments, such as shown in FIGS. 8-11 , the outer columns 850are only configured to fold up or down from the erected configuration tothe collapsed configuration. For example, a given outer column 850 mayonly be associated with a cross-beam upper track 810 or a cross-beamlower track 820, which can make the given outer column 850 only operableto fold up or down from the erected configuration to the collapsedconfiguration. In the example of FIGS. 8-11 , the floating wind turbine100 only has two cross-beam upper tracks 810 and two cross-beam lowertracks 820, which makes it such that the first pair of outer columns850B, 850C are only configured to fold downward and the second pair ofouter columns 850A, 850D are only configured to fold upward.

However, in some embodiments one or more of the outer columns 850 can beconfigured for bi-directional folding and can, for example, have bothupper and lower cross-beam tracks 810, 820. Also, in some embodiments,each of the outer columns 850 can be separately actuated or can beconfigured to always be actuated as a group. For example, the first pairof outer columns 850B, 850C can be configured to be actuated together asa group; the second pair of outer columns 850A, 850D can be configuredto be actuated together as a group; all four outer columns 850A, 850B,850C, 850D can be configured to be actuated together as a group, or thelike.

In various embodiments, a floating wind turbine 100 can be configured inpieces for assembly and/or disassembly, which can be desirable fortransportation as discussed herein. For example, the upper truss members860, lower truss members 870, and/or cross-beams 880 can have couplings(e.g., via pins, bolts, or the like) that allows such elements to beeasily coupled and de-coupled with the central column 840 and/or outercolumns 850 such that the upper truss members 860, lower truss members870, and/or cross-beams 880 can be separable from the central column 840and/or outer columns 850, which can allow the outer columns 850 and suchelements to be separated from each other and the central column 840. Insome embodiments, the central column 840 can be separated from the tower110. Additionally, in various embodiments, elements such as the nacelle170, blades 174, rotor and the like can be configured to be disassembledfrom each other and/or the tower 100. For example, in variousembodiments, one or more of such couplings can be non-permanentcouplings instead of a weld or other integral coupling.

A single floating wind turbine 100 or an array of a plurality offloating wind turbines 100 can be manufactured, erected or positioned invarious suitable ways with various portions occurring on land and/or abody of water 102. For example, in some embodiments, elements such as atower 110, nacelle 170, blades 174, central column 840, outer columns850, upper truss members 860, lower truss members 870, and/orcross-beams 880 can be manufactured separately and transported in adisassembled, partially assembled, or fully assembled form from amanufacturing location to a port, dock, or other location at a body ofwater 102.

For example, using FIGS. 8-11 as an illustration, in some embodimentsthe hull assembly 830 can be fully assembled (and may or may not becoupled with a tower 110) and transported to a body of water 102 in acollapsed configuration (see e.g., FIG. 10 ). In some examples, thecentral column 840, outer columns 850, upper truss members 860, lowertruss members 870, and/or cross-beams 880 can be manufactured separatelyand transported to a body of water in a disassembled set and assembledat the body of water 102. In various embodiments, it can be necessaryfor the tower 110 to be present in a collapsed configuration so thatouter columns 850 folding up can engage the tower 110 instead ofover-folding or undesirably moving in the collapsed configuration.

In some embodiments, with the tower 110 integrated onto the hullassembly 830 on or near land, in various examples the assembled floatingwind turbine 100 can be towed from a port to a location on a body ofwater 102 where the floating wind turbine 100 will be installed. Manyports have draft or air draft restrictions as previously described,which can be the distance from the surface of the water 101 to a highestpoint on a vessel, cargo on a vessel or cargo being towed by a vessel.Draft restrictions can be less than or equal to 7 m, 8 m, 9 m, 10 m, 12m or the like. Air draft restrictions can be less than or equal to 35 m,40 m, 45 m, 50 m, 55 m, 60 m, 70 m, 75 m, 80 m, 85 m, 90 m, or the like.Once these obstructions or restrictions have been cleared, the floatingwind turbine 100 can be reconfigured to have a larger draft, or a largerair draft or both a larger draft and a larger air draft. For example,the floating wind turbine 100 can be configured from a collapsedconfiguration to an erected configuration, where the collapsedconfiguration is compliant or compatible with obstructions orrestrictions (e.g., draft restrictions), but where the erectedconfiguration would not be compliant or compatible with one or both ofobstructions and restrictions.

Using FIGS. 8-11 as an example, in various embodiments, the process toupend a floating wind turbine 100 can include one or more fore floats(e.g., first and fourth outer columns 850A, 850D) and/or the centralcolumn 840 being filled with ballast (e.g., water from a body of water102 that the floating wind turbine 100 is disposed in) so that the oneor more fore floats (e.g., first and fourth outer columns 850A, 850D)are sunk within the body of water 102 and reach an extendedconfiguration (e.g., as shown in FIG. 11 ). In doing so, the cross-beams880 can have transited along their respective upper tracks 810 and canbe (e.g., temporarily) locked into place.

In various embodiments, sinking of the floating wind turbine 100 intothe body of water 102 below the water line (e.g., based on filling oneor more columns 840, 850 with ballast) can cause one or more aft floats(e.g., second and third columns 850B, 850C) to move from a collapsedconfiguration (e.g., as shown in FIG. 10 ) to an extended configuration(e.g., as shown in FIG. 11 ). For example, where the floating windturbine 100 has been sunk to a sufficient level within the body of water102, the buoyancy of the one or more aft tanks (e.g., second and thirdcolumns 850B, 850C) can cause cross-beams 880 of such aft tanks totransit across the lower tracks 820 and reach an extend position, asdepicted in FIG. 11 .

The cross-beams 880 can be (e.g., temporarily) locked into place, andthe floating wind turbine 100 can be upended in various embodiments toan erected configuration by (e.g., partially) evacuating the forefloat(s) (e.g., first and fourth columns 850A, 850D) and/or centralcolumn 840 while partially filling the aft float(s) (e.g., second andthird columns 850B, 850C). The change in ballast can produce a largeuprighting moment, which can cause the floating wind turbine 100 andturbine 700 to upright from a configuration as shown in FIG. 11 andreach an operational erected configuration such as shown in FIG. 8 . Insome embodiments, a cross-beam 880 can be locked into place by insertinga pin into the cross-beam 880 which prevents the cross-beam fromtranslating. Such a pin insertion in some examples can be triggeredremotely such as by an operator on a support vessel, or the like.

In some embodiments, outer columns 850 can be extended one-by-one.Additionally, in some embodiments, the floating wind turbine 100 canrotate (e.g., about the main axis Y) based on ballast being introducedand/or removed from columns 850, which may be desirable for making iteasier for the outer columns 850 can be extended one-by-onesequentially. For example, a first collapsed downward-facing outercolumn 850 can be extended based on ballast being added to this firstcollapsed outer column 850 to cause it to sink and become extended.Changing the buoyancy of one or more of the outer columns 850 can causethe floating wind turbine 100 to rotate and cause a second collapsedouter column 850 to be oriented downward such that the second collapsedouter column 850 can sink downward and extend. Further collapsed columns850 can be extended sequentially in a similar manner.

In some embodiments, in such an operational erected configuration, thelower truss members 870 can be fully submerged within a body of water102 below the surface 101 of the water 102; the central and outercolumns 840, 850 can be partially submerged in the water 102, with abottom portion submerged within the body of water 102 below the surface101 and a top portion out of the water 102 above the surface 101; theupper truss member 860 can be above the surface 101 of the water 102;and the tower 110 can be above the surface 101 of the water 102. Invarious embodiments, the level of the central and outer columns 840, 850above/below the surface 101 of the water 102 can be changed based on anamount of ballast and/or air in ballast tanks of the central and outercolumns 840, 850.

In some embodiments, movement of some or all of the outer columns 850from a collapsed configuration (e.g., FIG. 10 ) to an extendedconfiguration (e.g., FIG. 11 ) can be completely based on buoyancyand/or gravity. For example, motorized or other active powered actuationof the upper truss members 860, lower truss members 870, and/orcross-beams 880 can be absent. In other words, in some embodiments,changing the configuration of the floating wind turbine 100 between acollapsed configuration and an extended configuration can besubstantially or completely based on ballast or air being introduced orremoved from the central column 840 and/or outer columns 850.

In one embodiment, ballast pumps are located on the floating windturbine 100 and can be remotely operated to enact the filling of theballast tanks (e.g., of the central column 840 and/or outer columns850). In another embodiment, the ballast tanks (e.g., of the centralcolumn 840 and/or outer columns 850) are filled by opening a valve onthe column via a remotely operated vehicle (ROV) or diver. In anotherembodiment, the ballast tanks are connected via a hose to ballast pumpsonboard a support vessel such as a boat, ship or the like. In such anembodiment such ballast tanks can be filled and evacuated using the samepump run in reverse.

In various examples, after the floating wind turbine 100 is erected andconnected to electrical cable systems 155 and/or mooring systems 150,the turbine 700 can be commissioned for attachment to the floating windturbine 100; however, in some embodiments the turbine 700 can beinstalled onshore or in transit on water to an installation location andcan be present when the floating wind turbine 100 is erected. Forexample, in some embodiments an upending maneuver can be performed withthe nacelle 170 and blades 174 pre-installed or an upending maneuver canbe performed without the nacelle 170 and blades 174 being pre-installedwith such elements being added on after the upending maneuver. Someembodiments can include a nacelle 170 and blades 174 that can bepre-assembled horizontally.

As previously described, if the floating wind turbine 100 is to returnto port for maintenance, decommissioning, or the like, such aninstallation or erection method can be reversed in part or in whole.This can decrease the draft of the floating wind turbine 100, allowingit to enter a port with draft restrictions or to access shallow water.Furthermore, the tower 110 can be moved into a horizontal position invarious examples without the need for large tugboats when the verticalcenter of gravity aligns with or is close to the tower axis X. In someembodiments, the floating wind turbine 100 can be loaded on to a barge(e.g., submersible barge), for transport to or from shore.

Accordingly, a method of installing at least one floating wind turbine100 can include one or more of the follow steps, which can start withassembling portions of the tower 110 and hull assembly 830 and thencoupling the tower 110 to the hull assembly 830. Some or all of suchassembly can occur on land including at a port or shoreline, or awayfrom a port or shoreline. For example, the tower 110 and hull assembly830 (or portions thereof) can be transported to a port or shoreline asseparate pieces, with the tower 110 and hull assembly 830 (or portionsthereof) being assembled to form a full or substantially completefloating wind turbine 100. In one example embodiment, each of the tower110 and hull assembly 830 can be assembled in parallel. For example, anouter column 850 can be attached to a lower and upper truss member 860,870, as well as a cross-beam 880 during assembly of the tower 110.

In one embodiment, a lower section of the tower 110 and a tower base aremated. The central tower 110 can be lifted off the ground with temporarysupports such that fore floats (e.g., first and fourth outer columns850A, 850D) can be connected underneath. For example, the two forefloats can be connected to the central column 840 (e.g., via a pinbearing). The two aft floats (e.g., second and third outer columns 850B,850C) can be connected to the central column 840 (e.g., via a pinbearing). Remaining sections of the tower, such as the nacelle, rotor,and the like can be attached to the tower shaft 112.

Such a full or substantially complete floating wind turbine 100 can havethe tower 110 in a horizontal or near horizontal configuration whilebeing assembled and/or during a portion of a journey from a port orshoreline to a desired location where the floating wind turbine 100 isto be installed. In one embodiment, the turbine can be mated with thetower base in the horizontal position. Such an embodiment can usesmaller, more readily available cranes to lift the tower sections,nacelle and blades (e.g., a gantry crane). Before, during, or just afterthe turbine installation, solid ballast can be added to the central orouter columns 840, 850 to lower the center of gravity of the structure.In one embodiment, the solid ballast can take the form of batteries.

In another embodiment, the platform is towed with the turbine in thehorizontal position so that the drag on the turbine can be reduced. Inone such an embodiment, the turbine upending can occur at the wind farmsite. For example, when possible or desirable, the floating wind turbine100 can be converted from the tower 110 being in the horizontal or nearhorizontal configuration to an erected configuration where the tower 110is in a vertical or near vertical configuration, so it can be connectedto a mooring and cabling system.

In some embodiments, once a turbine has been integrated onto tower 110,in various examples the floating wind turbine 100 can be towed fromport. Many ports have draft or air draft restrictions as previouslydescribed. In one embodiment, the fully assembled floating wind turbine100 can be transported on a barge. In another embodiment, the fullyassembled floating wind turbine 100 can be skidded directly into thewater (e.g., in a collapsed form such as shown in FIG. 10 ) and towedvia tow lines 410. In another embodiment, the floating wind turbine 100can be assembled in a dry dock, which can be filled with water after theassembly process is completed. Then, the assembled floating wind turbine100 can be towed out of the port and to an offshore location (e.g., windfarm site), which in some examples can be via standard tug boats Thefloating wind turbine 100 can be transported in some examples by suchvehicles as self-propelled modular transports, which are commonly usedin port facilities. In this manner, the fully assembled floating windturbine 100 can be loaded on to a barge for offshore transport.

In various embodiments, once the port obstructions, restrictions orshallow water have been cleared, the floating wind turbine 100 can beupended. For example, the floating wind turbine 100 can be towed out ofport via tow lines 410 in the collapsed configuration as shown in FIG.10 with ballast (e.g., water) absent or substantially absent fromcentral or outer columns 840, 850.

The floating wind turbine 100 can be upended from a collapsedconfiguration (e.g., as shown in FIG. 10 ) by a first set of one or morecolumns 850 (e.g., first and fourth outer columns 850A, 850D) and/or thecentral column 840 being filled with ballast (e.g., water) to change thebuoyancy of the first set of one or more columns 850 so that the firstset of one or more columns 850 sink within the body of water 102 andreach an extended configuration (e.g., as shown in FIG. 11 ). In variousembodiments such a configuration change can include the cross-beams 880of the first set of one or more columns 850 translating along theirrespective upper tracks 810.

In various embodiments, such as shown in the example of FIG. 11extension of the first set of one or more columns 850 can include thefirst set of one or more columns 850 going from being partiallysubmerged in the water 102 to being fully submerged within the water 102and can include the central column 840 going from being partiallysubmerged in the water 102 to being fully submerged within the water102.

In various embodiments, a second set of one or more columns 850 (e.g.,second and third columns 850B, 850C) can move from a collapsedconfiguration (e.g., as shown in FIG. 10 ) to an extended configuration(e.g., as shown in FIG. 11 ). For example, the buoyancy of the secondset of one or more columns 850 can cause cross-beams 880 of the secondset of one or more columns 850 to translate along the lower tracks 820and reach an extend position, as depicted in FIG. 11 . In someembodiments, the second set of one or more columns 850 can remainfloating on the surface 101 of the body of water 102 with a portion ofthe second set of one or more columns 850 disposed in the water 102 anda portion of the second set of one or more columns 850 remaining out ofthe water throughout the transition of the second set of one or morecolumns 850 from the collapsed configuration to the extendedconfiguration.

In some embodiments, extension of the first set of one or more columns850 and extension of the second set of one or more columns 850 can occursimultaneously or can occur sequentially in any suitable order. In someembodiments, sinking of the first set of one or more columns 850 andcentral column 840 into the body of water 102 can cause extension of thesecond set of one or more columns 850 based on the second set of one ormore columns 850 remaining floating on the surface 101 of the body ofwater 102 based on the buoyancy of the second set of one or more columns850.

The floating wind turbine 100 can be upended in various embodiments toan erected configuration by removing ballast from the first set of oneor more columns 850 and/or central column 840. Additionally, in someexamples, the second set of one or more columns 850 can be at leastpartially filled with ballast during such an upending. Such a change inballast of the first and/or second sets of one or more columns 850 cangenerate an uprighting moment, which can cause the floating wind turbine100 to upright from a configuration as shown in FIG. 11 and reach anoperational erected configuration such as shown in FIG. 8 .

In some embodiments, the first and second sets of one or more columns850 can be filled with the same amount of ballast to generate equalbuoyancy of the first and second sets of one or more columns 850 or theballast of the first and second sets of one or more columns 850 canotherwise be configured to generate equal buoyancy of the first andsecond sets of one or more columns 850 (e.g., different amounts ofballast for columns having different weight).

While various examples of a floating wind turbine 100 can include fourouter columns 850A, 850B, 850C, 850D, further embodiments can includeany suitable number of columns 850 as discussed herein, including 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 25, 100, and the like. For example,FIG. 12 illustrates an example embodiment of a floating wind turbine 100having three outer columns 850A, 850B, 850C.

In this example, the three outer columns 850A, 850B, 850C are shownequally spaced about the central column 840 with respective adjacentouter columns 850 being 120° from each other about the central axis Y,which can define three planes of symmetry that are coincident with thecentral axis Y. It should be clear that descriptions of embodimentshaving four outer columns 850 can be equally applicable to embodimentshaving other numbers of outer columns 850 (e.g., three) in accordancewith some examples.

Additionally, an embodiment 100D of a floating wind turbine 100 havingthree outer columns 850A, 850B, 850C such as shown in FIG. 12 (or othernumber of outer columns 850) can fold or otherwise assume a collapsed,expanded and/or erected configuration as discussed in other exampleembodiments herein. Using FIG. 12 as an example, one or two columns 850of the three outer columns 850A, 850B, 850C can be configured to foldupward (e.g., like first and fourth columns 850A, 850D shown in FIG. 10) and one or two other columns 850 of the three outer columns 850A,850B, 850C can be configured to fold downward (e.g., like second andthird columns 850B, 850C shown in FIG. 10 ). Similarly, introductionand/or removal of ballast from respective columns 850 can cause fore andaft sets of one or more columns 850 to extend and/or contract and tocause the floating wind turbine 100 to be upended or lowered asdiscussed herein. Outer columns 850 can be configured to move via tracks810, 820 as discussed herein or such tracks 810, 820 can be absent. Insome such embodiments where tracks 810, 820 are absent, the stiffness ofthe upper and/or lower truss members 860, 870 can keep the column 850aligned during the unfolding process. In some examples, the end of across-beam 880 can be attached to a winch line that guides thecross-beam 880 into a final position in a controlled manner. Once thecross-beam 880 reaches a final position, a pin can be inserted into thecross-beam 880 to lock the cross-beam 880 into place.

Also, as shown in the example of FIG. 12 , the floating wind turbine 100can comprise various access elements 890, which can include one or moreladders 892, one or more outer column platforms 894, one or morewalkways 896 and one or more central column platform 898, and the like.For example, when the floating wind turbine 100 is floating in a body ofwater 102, a boat or ship can dock with the floating wind turbine 100and a human operator can climb a ladder 892 on one of the outer columns850 to the outer column platform 894, across the walkway 896 and to thecentral column platform 898. In various examples, the tower 110 canhouse elements of the floating wind turbine 100 that can be accessed bythe human operator for purposes of maintenance, repair, or the like.Additionally, in various examples, there can be a ladder within thetower body 112, which allows an operator to climb up to the nacelle 170for purposes of maintenance, repair, or the like, of elements of theturbine 700.

Additionally, while various embodiments can include a plurality of outercolumns 850 radiating from a central column 840, further embodiments caninclude columns 840, 850 in any suitable configuration with a centralcolumn 840 being absent in some embodiments. For example, a set of outercolumns 850 can be disposed in a triangular, quadrilateral, pentagonal,hexagonal, heptagonal, octagonal arrangement, or the like, with acentral column being absent. Additionally, while various embodimentsillustrated herein include a tower 110 extending from a central column840, in further embodiments, one or more towers 110 can extend from oneor more outer columns 850, including in some embodiments where a centralcolumn 840 is present.

One embodiment comprises, consists essentially of, or consists of adownwind and/or upwind floating wind turbine 100 with a turbine controlsystem that can be used to optimize the tilt angle of the floating windturbine 100 or portions thereof. Another embodiment comprises, consistsessentially of, or consists of a downwind and/or upwind floating windturbine 100 with a teetered hub, and a turbine control system that canbe used to optimize the teeter angle of the rotor and the tilt angle ofthe floating wind turbine 100 or portions thereof.

In some such embodiments, no active control system exists on thefloating wind platform, as the floating wind turbine 100 can be allowedto passively pitch in the direction of the wind. However, in variousexamples, the wind turbine 700 is able to produce full power, as a rotorplane of the floating wind turbine 100 can remain aligned with thehorizontal.

Turning to FIGS. 13 a, 13 b, 14 a, 14 b and 15 , various embodiments ofa floating wind turbine 100 are illustrated that comprise a tower 110disposed on a hull assembly 830 with a wind turbine 700 disposed on thetop of the tower body 112 of the tower 110. The wind turbine 700comprises a nacelle 170 with a hub 172 and a plurality of blades 174extending from the hub 172. The 110 tower can have a central axis Y. Thehub 172 and blades 174 can rotate about a rotor axis R, with the blades174 having a blade plane B that is perpendicular to the rotor axis R.

In various embodiments, the hub 172 and corresponding rotor axis R canhave a rotor tilt angle defined by a difference between the rotor axis Rand a horizontal axis H (i.e., an axis perpendicular to gravity) whenthe central axis Y of the tower 110 is completely vertical (i.e., thecentral axis Y is parallel with an axis of gravity). For example, FIG.13 a illustrates an example where the central axis Y of the tower 110 isat a heel angle of 0° (i.e., the central axis Y is parallel with an axisof gravity), and the horizontal axis H is perpendicular to the centralaxis Y of the tower 110. The rotor axis R in this example is 5° from thehorizontal axis H, which defines the rotor tilt angle of the example ofFIG. 13 a as being 5°. In some embodiments, rotor tilt angle can bedefined based on a difference in angle between the central axis Y andblade plane B.

Turning to FIG. 13 b , the floating wind turbine 100 of FIG. 13 a isshown having a heel angle of 10° (i.e., the central axis Y of the tower110 is 10° from true vertical as shown in FIG. 13 a ). Here, the heelangle of 10° plus the rotor tilt angle of 5° means that the rotor axis Ris 15° from the horizontal axis H in this example. In variousembodiments, having the rotor axis R parallel with the horizontal axis H(e.g., 0° misalignment) can be considered to be an optimal configurationfor a wind turbine 700 (e.g., because such a configuration can maximizethe swept area by the blades 174); accordingly, in such embodiments, therotor axis R being 15° from the horizontal axis H can be considered a15° misalignment of the rotor axis R from an optimal configuration.

However, in further embodiments, any suitable axis can be defined as anoptimal axis for the rotor axis R, which can be based on wind direction,wind angle, or the like. In some examples, such an optimal axis for therotor axis R can change based on changing environmental conditions(e.g., changing wind direction, wind angle, or the like) or can remainthe same even if environmental conditions change.

In various embodiments, such misalignment of the rotor axis R can bedesirable or acceptable for various reasons, but may come at the cost ofreduced energy production; for example, a reduction in Annual EnergyProduction (AEP), or the like. In some embodiments, a reduction in AEPcan be considered acceptable or can be unacceptable. For example, insome embodiments, a reduction in AEP of less than or equal to. 1%, .2%,.3%, .4%, .5%, .6%, .7%, .8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or thelike can be considered acceptable. in some embodiments, a reduction inAEP of greater than or equal to 1%, 1.5%, 2%, 2.5%, 3%, 3.1%, 3.2%,3.3%, 3.4%, 3.5%, 4%, 4.5%, 5% or the like can be consideredunacceptable. Accordingly, various embodiments of a floating windturbine 100 can be configured to operate at mean heel angle with a rotortilt angle that generates a rotor misalignment that creates a reducedenergy production compared to optimal (e.g., reduced AEP) that isconsidered acceptable or that is not considered unacceptable.

A floating wind turbine 100 of some various embodiments includes adownwind turbine 700, where the rotor is oriented 4° to 8° upward fromthe horizontal H in order to increase the clearance between the bladetips and tower shaft 112 in operation. The floating wind turbine 100 invarious examples produces a thrust force in order to produce power fromthe wind. The thrust force can result in an overturning moment offloating wind turbine 100, which can cause the floating wind turbine 100to have a mean heel angle. In some examples, a mean heel angle can bethe mean pitch angle of the floating wind turbine 100, in the directionof the wind. In some embodiments, the mean heel angle can be 0°, 1°, 2°,3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°,19°, 20°, or the like, or a range between such example values.

In some examples of a floating wind turbine 100, the target design heelangle is the heel angle of the platform when it is subject to the ratedthrust force of the turbine. Rated thrust force can be the maximum meanthrust force on the turbine during operation. The design heel angle of aplatform can depend on the platform’s hydrostatic stiffness, which canbe a function of its center of gravity and buoyancy, its waterplanemoment area of inertia and the restoring force due to a mooring system.In some examples, increasing the floating wind turbine 100 hydrostaticstiffness can result in increased cost or complexity of the system, orboth. For instance, for some semi-submersible floating wind turbines100, the hydrostatic stiffness can be increased by increasing thespacing of the columns 840, 850, increasing the size of the columns 840,850, or both.

Floating wind turbines 100 of some embodiments without active controlsystems, can target a design heel angle of 4-5 degrees, so that that themaximum rotor misalignment is 8-13 degrees from the horizontal axis H.Some floating wind turbines 100, with active platform control systems,can target a design heel angle of 5-8 degrees, so that that the tower110 can remain vertical and the maximum rotor misalignment can bemaintained at 4-8 degrees. Some wind turbines can have larger activecontrol systems which can cause an increased tilt angle, resulting in 0degrees rotor misalignment. In some embodiments, a floating wind turbinecan be configured to operate with a rotor misalignment of -20°, -19 °,-18 °, -17 °, -16 °, - 15°, -14°, -13°, -12°, -11°, -10°, -9 °, -8 °, -7°, -6 °, - 5°, -4°, -3°, -2°, -1°, 0°, 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°,9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, or the like,or a range between such example values.

In various embodiments, a benefit of a tilting floating wind turbine 100operating at a tilt angle can be that a wake generated by the floatingwind turbine 100 can be driven into the body of water 102 and can have areduced effect on the downstream floating wind turbine 100 where aplurality of floating wind turbines 100 are disposed in an array, groupor farm. In various embodiments, this can allow more floating windturbines 100 to be grouped into in a given area, which can be desirablefor operators of floating wind turbines 100.

In various embodiments, the design heel angle of the floating windturbine 100 can be increased to 10-15 degrees, which in some examplescan allow for a much smaller floating wind turbine 100 and/or lesscomplex mooring system, or the like. In some embodiments, if the rotortilt angle is 5 degrees above the horizontal axis H, the floating windturbine 100 can heel under the influence of the rated thrust on thefloating wind turbine 100. If the design heel angle of the turbine is 10degrees, in various embodiments the rotor misalignment is only 5 degreesbelow the horizontal, which can be the same magnitude of misalignment asa conventional wind turbine with 0 degrees heel angle (e.g., orientedvertically).

While various examples can include a rotor tilt angle of 5°, variousother rotor tilt angles can be defined in further embodiments including-10°, -9°, -8°, -7°, -6°, -5°, -4°, -3°, -2°, -1°, 0°, 1°, 2°, 3°, 4°,5°, 6°, 7°, 8°, 9°, 10°, or the like, including a range between suchexample values. In some embodiments, the rotor tilt angle can be definedby various portions of a wind turbine 700 such as the physical positionof the nacelle 170, hub 172, and the like. In some embodiments, therotor tilt angle can be fixed based on a physical configuration of thewind turbine 700 or can be changeable in some embodiments (e.g.,motorized tilting of the nacelle 170 to change the rotor tilt angle).

In various embodiments, the floating wind turbine 100 can be configuredto have or can be positioned to heel angle or operating angle (e.g.,angle of the central axis Y relative to true vertical) based onweighting or balancing of the hull assembly 830 (e.g., based on amountof ballast in columns 840, 850), weights of various portions of the hullassembly 830, tower 110 and/or wind turbine 700, anticipated or actualwind speed and/or direction, and the like. For example, in variousembodiments, wind force on the floating wind turbine 100 can cause thefloating wind turbine to be angled. Additionally, in various examples,wind, waves or tidal action of a body of water 102 can cause thefloating wind turbine 100 to rock or otherwise move within the body ofwater 102. Accordingly, the floating wind turbine 100 can be configuredto operate within a range of heel angles. For example, in someembodiments, the floating wind turbine 100 can be configured to beangled -20°, -19°, -18°, -17°, -16°, -15°, -14°, -13°, -12°, -11°, -10°,-9°, -8°, -7°, -6°, -5°, -4°, -3°, -2°, -1°, 0°, 1°, 2°, 3°, 4°, 5°, 6°,7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, orthe like, or a range between such example values.

Additionally, a floating wind turbine 100 can be configured for upwindand/or downwind operation. An example of upwind operation is illustratedin FIGS. 13 a and 13 b where the direction of wind is toward the frontface of the hub 172 and blades 174 and then moving over the nacelle 170.In contrast, FIGS. 14 a, 14 b and 15 illustrate examples of downwindoperation where the direction of wind is toward the rear face of the hub172 and blades 174 with wind directed toward the rear of the nacelle170.

For example, FIGS. 14 a and 14 b illustrate an example where the rotorplane R is 5° away from the perpendicular to the shaft axis Y to definea rotor tilt angle of 5°. As shown in FIG. 14 b , where the floatingwind turbine becomes angled 10° (e.g., based on wind, balance, or thelike), this can cause the rotor axis R to be -5° from the horizontalaxis H. In another embodiment the design heel angle can be 20 degrees,with 10 degrees of misalignment between the rotor plane R and the shaftaxis Y.

In some examples, a downwind, teetering floating wind turbine 100 ofvarious embodiments can afford the platform designer with even a largerdesign heel angle, while still maintaining 0 degrees of rotormisalignment. In some examples of a teetered floating wind turbine 100,the rotor axis R can be misaligned from an angle that is perpendicularto the main shaft axis Y. For example, FIG. 15 illustrates such anexample. The platform can have a 15° design heel angle as shown in thisexample, but has 0 degrees of rotor misalignment with the incident winddue to the additive effects of the downwind turbine and a teetered hub1500 that allows for movement of the hub relative to the rotor axis R.In this way, in various examples the cost and complexity of the platformand mooring system can be decreased even further from using a fixed hub,downwind wind turbine.

In various embodiments, a floating wind turbine 100 can have varioussuitable control systems such as blade pitch controllers, nacelle yawcontrol, generator torque control, and the like. In various embodiments,a floating wind turbine 100 can comprise a computing system comprising aprocessor and memory that stores instructions, that when executed by theprocessor, cause various methods to be performed. In variousembodiments, such a computing system can obtain data from varioussuitable sensors such as one or more accelerometer, temperature sensor,water sensor, humidity sensor, magnetic field sensor, gyroscope,pressure sensor, torque sensor, light sensor, rain gauge, wind sensor,current sensor, depth sensor, GPS unit and the like. For example, sensordata from such sensors can be used to determine position, tilt angle,orientation, velocity, power generation, turbine speed, depth within abody of water, and other states or configurations of the floating windturbine 100. Additionally, in some examples, sensor data from suchsensors can be used to determine environmental conditions such as airtemperature, water temperature, water salinity, wind speed, winddirection, wave height, wave direction, precipitation, and the like.Various examples can include systems and methods to control the bladepitch of the blades 174 to optimize power production from a floatingwind turbine 100.

As a floating wind turbine 100 is subject to dynamic wave loads, invarious embodiments the floating wind turbine 100 can undergo dynamicpitch motion. The magnitude of the pitch motion of the floating windturbine 100 can be related to the magnitude of the variation in theseenvironmental forces, as well the characteristics of the floating windturbine 100, such as its pitch stiffness, damping and the like. In someembodiments, the floating wind turbine 100 can exhibit dynamic pitchmotion up to 5° in amplitude. For example, for a floating wind turbine100 with a design mean heel angle of 15 degrees, the platform couldpitch from 10-20 degrees away from the vertical. As the floating windturbine 100 is pitching back and forth, the relative wind velocity onthe blades 174 can change. If the blade pitch is not adjusted, in someexamples this could lead to unstable behavior of the floating windturbine 100.

In some examples, the power absorbed by the generator can beproportional to the relative velocity on the rotor to the power of 3. Ifwe approximate the sinusoidal motion of the platform as a step curve, sothat the relative velocity is either increased or decreased by aconstant value VV, in various embodiments we are able to increase thepower produced over one cycle. Mathematically, the power generated by afixed turbine can be proportional to the cube of the incident wind speedV_(∞):

P_(∞) ∝ V_(∞)³

Mathematically, the power generated by a wind turbine that is rockingback and forth can be proportional to the cube of the relative windspeed V_(rel) between the turbine and the wind:

P_(enh) ∝ V_(rel)³ = 0.5 * (V_(∞) − ∇V)³ + 0.5 * (V_(∞) + ∇V)³ = P_(∞) + 3V_(∞)∇V²

The power enhanced can be proportional to ∇V² which can be the square ofthe pitch velocity of the platform multiplied by the hub height. In someexamples, the instantaneous power enhancement is small. However, overthe lifetime of the floating wind turbine 100, the power enhanced can besignificant.

In order to achieve this power enhancement in various embodiments, thethrust force absorbed by the floating wind turbine 100 must remainrelatively constant over one pitching cycle of the floating wind turbine100. Natural periods in pitch for a floating wind turbine 100 can begenerally 20-30 s in some examples.

One embodiment of a wind turbine controller method 1600 is depicted inFIG. 16 . The purpose of the controller can be to determine the velocityof the rotor relative to the incident wind, by measuring or determiningthe positions, velocities and accelerations of the floating wind turbine100 as well as the incident wind speed and direction. Then, blade pitchcontrollers can be actuated to ensure that the thrust on the rotorremains relatively constant.

An ancillary benefit of such wind turbine control system in variousembodiments is that the amplitude of the variation of thrust force canbe minimized, resulting in reduced fatigue damage on the turbine 700 andhull assembly 830, and the like. The variation in the thrust force canresult in a bending moment on the base of the tower 110, which can betransferred to the hull assembly 830. By reducing the variation in theamplitude of the thrust force, in various examples the fatigue damageaccrued on the floating wind turbine 100 is reduced.

For example, referring to FIG. 16 , at 1610, position and/or orientationof the floating wind turbine 100 is measured or determined, which caninclude pitch, roll and yaw motions along with velocities,accelerations, and the like. In various examples such measurements ordeterminations can be based on sensor data obtained from sensors asdiscussed herein. At 1620, incident wind speed, incident wind direction,and the like, are measured or determined, which can be based on sensordata obtained from sensors as discussed herein.

At 1630, rotational motion, velocity and acceleration in line with winddirection can be determined, and at 1640, rotational motion, velocityand acceleration in line with wind direction over a time horizon (e.g.,20-30 seconds) can be predicted or determined. At 1650, a determinationcan be made for blade pitch angle(s) to minimize thrust variation and/ormaximize power production over the controller time horizon, and at 1660,a blade pitch system can be actuated to change the configuration of oneor more blades 174 in accordance with the determination at 1650.

The described embodiments are susceptible to various modifications andalternative forms, and specific examples thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the described embodiments are not to belimited to the particular forms or methods disclosed, but to thecontrary, the present disclosure is to cover all modifications,equivalents, and alternatives. Additionally, elements of a givenembodiment should not be construed to be applicable to only that exampleembodiment and therefore elements of one example embodiment can beapplicable to other embodiments. Additionally, elements that arespecifically shown in example embodiments should be construed to coverembodiments that comprise, consist essentially of, or consist of suchelements, or such elements can be explicitly absent from furtherembodiments. Accordingly, the recitation of an element being present inone example should be construed to support some embodiments where suchan element is explicitly absent. Additionally, use of the term“floating,” or the like, should not be construed to indicate that agiven element or system is currently floating and instead that such anelement is configured, configurable or capable of floating in a fluid.

What is claimed is:
 1. A system comprising: a tower that includes aturbine with a nacelle, hub and a plurality of blades extending from thehub, the tower having a central axis Y; a hull assembly that includes: acentral column coupled to a base of the tower at a top of the centralcolumn, the central column having a central column axis coincident withthe central axis Y, a plurality of outer columns, including no more thanthree outer columns, and including a first outer column, a second outercolumn and a third outer column, the plurality of outer columnssurrounding and equally spaced about the central column with respectiveadjacent outer columns being 120° from each other about the central axisY and can defining three planes of symmetry that are coincident with thecentral axis Y; a plurality of upper truss members, including at least afirst upper truss member, a second upper truss member and a third uppertruss member that respectively couple the first, second and third outercolumns with the central column and that extend from respective top endsof the first, second and third outer columns; a plurality of lower trussmembers including at least a first lower truss member, a second lowertruss member and a third lower truss member that respectively couple thefirst, second and third outer columns with the central column and thatextend from respective bottom ends of the first, second and third outercolumns; a plurality of cross-beams, including at least a first-crossbeam, a second cross-beam and a third cross-beam, that respectivelycouple the first, second and third outer columns with the central columnand that extend diagonally between respective upper and lower trussmembers; wherein the hull assembly is configured to assume an extendedconfiguration where the first, second and third upper truss membersextend between the central column and a respective outer column in afirst common plane; and the first, second and third lower truss membersextend between the central column and a respective outer column in asecond common plane that is parallel to the first common plane andperpendicular to the central axis Y; and the three outer columns haverespective outer column central axes that are parallel to each other;and wherein the hull assembly is configured to assume a collapsedconfiguration from the extended configuration, where one or two of thethree outer columns are configured to fold upward toward and proximateto the tower; and one or two other columns of the three outer columnsare configured to fold downward below and proximate to a base of thecentral column.
 2. The system of claim 1, wherein the central column andthe three outer columns are configured to be filled with water that actsas ballast for the hull assembly.
 3. The system of claim 1, wherein thesystem is configured to assume an erected configuration floating in abody of water, on a surface of the body of water, where the hullassembly is in the extended configuration and the tower extendsvertically above the surface of the body of water with the three outercolumns and the central column partially submerged in the body of water,with the system floating in the body of water at least based on buoyancyof the three outer columns and the central column.
 4. The system ofclaim 3, wherein the system in the erected configuration would violate aport draft allowance of 8-12 m and an air draft allowance of 50-70 m,but the system in the collapsed, horizontal configuration would notviolate the port draft allowance of 8-12 m nor the port air draftallowance of 50-70 m.
 5. A system comprising: a hull assembly thatincludes: a central column with a central axis Y, a plurality of outercolumns including a first outer column, a second outer column and athird outer column, the plurality of outer columns surrounding andequally spaced about the central column about the central axis Y; aplurality of upper truss members, including at least a first upper trussmember, a second upper truss member and a third upper truss member thatrespectively couple the first, second and third outer columns with thecentral column; a plurality of lower truss members including at least afirst lower truss member, a second lower truss member and a third lowertruss member that respectively couple the first, second and third outercolumns with the central column; and a plurality of cross-beams,including at least a first-cross beam, a second cross-beam and a thirdcross-beam, that respectively couple and extend diagonally between thefirst, second and third outer columns and the central column.
 6. Thesystem of claim 5, further comprising a tower extending from the hullassembly that includes a turbine.
 7. The system of claim 5, wherein thehull assembly includes no more than three outer columns.
 8. The systemof claim 5, wherein the hull assembly is configured to assume anextended configuration where the first, second and third upper trussmembers extend between the central column and a respective outer columnin a first common plane; and the first, second and third lower trussmembers extend between the central column and a respective outer columnin a second common plane that is parallel to the first common plane andperpendicular to the central axis Y.
 9. The system of claim 5, whereinthe hull assembly is configured to assume a collapsed configurationwhere one or two of the plurality of outer columns are configured tofold upward and one or two other columns of the plurality of outercolumns are configured to fold downward.
 10. A system comprising: a hullassembly that includes: a plurality of outer columns including a firstouter column, a second outer column and a third outer column, theplurality of outer columns surrounding and spaced about a central axisY.
 11. The system of claim 10, further comprising: a central column thatextends along the central axis Y; and a plurality of upper trussmembers, including at least a first upper truss member, a second uppertruss member and a third upper truss member that respectively couple thefirst, second and third outer columns with the central column.
 12. Thesystem of claim 10, further comprising: a central column that extendsalong the central axis Y; and a plurality of lower truss membersincluding at least a first lower truss member, a second lower trussmember and a third lower truss member that respectively couple thefirst, second and third outer columns with the central column.
 13. Thesystem of claim 10, further comprising: a central column that extendsalong the central axis Y; and a plurality of cross-beams, including atleast a first-cross beam, a second cross-beam and a third cross-beam,that respectively couple and extend diagonally between the first, secondand third outer columns and the central column.
 14. The system of claim10, further comprising a tower extending from the hull assembly.
 15. Thesystem of claim 10, wherein the hull assembly includes no more thanthree outer columns.
 16. The system of claim 10, wherein the pluralityof outer columns are configured to be filled with water that acts asballast for the hull assembly.
 17. The system of claim 10, wherein thehull assembly is configured to assume a collapsed configuration whereone or two of the plurality of outer columns are configured to foldupward and one or two other columns of the plurality of outer columnsare configured to fold downward.
 18. The system of claim 10, wherein thehull assembly is configured to assume an extended configuration where aplurality of upper truss members extend between a central column and arespective outer column in a first common plane; and a plurality oflower truss members extend between the central column and a respectiveouter column in a second common plane that is parallel to the firstcommon plane and perpendicular to the central axis Y.
 19. The system ofclaim 18, wherein the system is configured to assume an erectedconfiguration floating in a body of water, on a surface of the body ofwater, where the hull assembly is in the extended configuration and atower coupled to the hull assembly extends vertically above the surfaceof the body of water with the plurality of outer columns at leastpartially submerged in the body of water, with the system floating inthe body of water at least based on buoyancy of the plurality of outercolumns.
 20. The system of claim 19, wherein the system in the erectedconfiguration would violate a port draft allowance of 50-70 m, but thesystem in a collapsed configuration would not violate the port draftallowance of 50-70 m.